A Study on Determination of Electrical Impedance and Frequency Characteristics of a Subway System Using Finite Element Analysis

2013 ◽  
Author(s):  
Sorin Deleanu ◽  
David C. Carpenter
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Railway Track ◽  
Return Current ◽  
Rail Track ◽  
Current Path ◽  
Subway System ◽  
Subway Train ◽  
Analytical Approaches

The paper provides a description of the analysis of a subway system (track-in-tunnel) by using FEM analysis and comparing to classical analytical approaches by Carson, Pollaczek, Bickford and Tylavsky. Reviews of methods to determine self and mutual impedance for electrified railroads are provided. These methods include frequency response and are directly applicable to a three-rail track DC track system. The analytic impedance models are built on Carson-Pollaczek–Bickford equations, adjusted by Tylavsky, for two situations: when the ground is perfectly insulated and when considering the earth return current. For the latter, the authors assume a return current path only through the tunnel concrete structure below the railway track support structure. The model is extended by considering the effects of the soil beneath under tunnel as a conductor. The solution of finite element method (FEM) applied for the determination of impedance for the three-rail track subway train configuration, modeled and examined, consists of computational analysis based upon minimizing the energy of electromagnetic field. The paper continues by examining the frequency effects on the track and system. The track/trolley model developed by Tylavsky was modified such that the trolley feeder is provided by the power rail and used to calculate the return current through the traction rails. The subway train, supplied with a rectified DC power, is subjected to a significant harmonic content, which may affect the signal and control circuits. Both experimental data and preliminary analytical and numerical calculations are presented, showing the variation of resistances and inductances of the running track with the current magnitude and frequency response. In the study, a large frequency range was considered (15Hz to 5000Hz) in order to cover all of the significant frequencies used for control and signal systems in common tracks configurations, and for which measurements have been carried. It is then shown that the power and signaling characteristics of the modeled system can predict the magnitude of the perturbation current for different values of frequency. The current density profile is illustrated for the case of a concrete tunnel structure in a subway application. The last section consists of a discussion regarding future developments and further work.

An Extended Model of Light Railway System Used in Analysis of Normal Operation and Fault Conditions

2014 ◽  
Author(s):  
Sorin Deleanu ◽  
Keith Forman ◽  
David C. Carpenter ◽  
Calin Munteanu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Short Circuit ◽  
Operating Conditions ◽  
Normal Operation ◽  
Dc Power ◽  
Railway System ◽  
Analytical Approaches ◽  
Element Method

The paper provides a description of the analysis of a Light Railway System for two configurations: - Rails above the ground and catenary supply - Track in a tunnel and power rail supply. Finite Element Method (FEM) analysis is compared to classical analytical approaches by Carson, Pollaczek, Bickford and Tylavsky. Reviews of methods to determine self and mutual impedance for electrified railroads are provided. The solution of finite element method (FEM) applied for the determination of impedance for the two traction rail and catenary configuration, modeled and examined, consists of computational analysis based upon minimizing the energy of electromagnetic field. The analytic impedance models are built on Carson-Pollaczek–Bickford equations, adjusted by Tylavsky, for two situations: when the ground is perfectly insulated and when considering the earth return current. The railway track – catenary is integrated in a system containing the model for traction substation(s) with DC power output and moving vehicle with induction motors, controlled using voltage inverters with pulse width modulation. The light transit train, supplied with a rectified DC power, is subjected to a significant harmonic content, which may affect the signal and control circuits. It is then shown that the power and signaling characteristics of the modelled system can predict the magnitude of the perturbation current for different frequencies, in normal operating conditions and in presence of faults as well. In many of the light transportation systems, from all types of faults, the DC short-circuit at the output of the power rectifiers used for energizing the power rail and/or catenary presents a special interest. This is because of two main reasons: the positions of the vehicle-loads are in continuous changing and, even if they operate from DC sources, the parent network is still of AC type. A key issue was the determination of the distributed parameters (resistances, inductances) of the running track and catenary, from experimental data and preliminary analytical and numerical calculations, followed by the analysis of their dependencies with the current magnitude and frequency response. A specific short-circuit study case is simulated when using a model of the traction system for the purpose of the DC fault current prediction. The paper concludes with a discussion of future developments and further work.

scholarly journals Determination of the maximum dangerous width of a rail track on a reinforced concrete base with fasteners of the КБ type, taking into account all influencing factors

2021 ◽  
pp. 113-120
Author(s):  
Vadym Novikov ◽  
Andriy Babenko ◽  
Oleksandr Kharkivskyi ◽  
Olena Olexandrivna Tkachenko
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
Railway Track ◽  
Rolling Stock ◽  
Lateral Direction ◽  
Maximum Width ◽  
Rail Track ◽  
Emergency Braking ◽  
Simultaneous Influence

Railway track retention standards in Ukraine do not take into account theconstruction of the subrail base, but regulate one for all types maximum dangerous value of the trackwidth, which was changed from 1546 mm to 1548 mm without any justification of scientific researchor explanations of the effects of tolerances the width of the rail track and the wheel track, which ingeneral at that time were not fully investigated but taking into account the emergence anddevelopment of new scientific problems associated with the emergence of intensive lateral wear ofrails and ridges of locomotive and wagon wheels. The deterministic dependences of lateralimpressions of the P65 type rail thread head on the simultaneous influence of vertical and horizontalforces for the newly installed repair profiles of UZ rolling stock on the basis of previously performedexperimental and theoretical studies were investigated. The results allow at this stage of research todetermine and calculate the practical values of the maximum dangerous width of the track, in whichthe subrail base consists of reinforced concrete sleepers and separate rail fasteners, which are usedboth on conventional highways with mixed traffic and on high-speed lines UZ.The article establishes the need to take into account new factors influencing the dangerouswidth of the rail track with intermediate rail fasteners of separate type depending on the load stress of sections and new repair profiles of rolling stock, as well as wear processes of intermediate railfasteners type KБ and its elements on the appearance of elastic backlash in the lateral direction fromthe influence of the guide wheels of the rolling stock. The recommended value of the maximum widthof the rail track for areas where service or emergency braking is applied - 1550 mm, taking intoaccount that the contact of the wheel and the rail is not at a point, but on an ellipse. The establishednorm of the maximum width of a rail track allows to define economic efficiency of introduction in theconditions of operation of a track in curved sections of a track of small radii with limited use of themaximum admissible lateral wear (15 mm) of a head of a rail thread provided that the normal-forcedentry of rolling stock carts.

Determination of Full Set Elastic Constants for Composite Materials on Basis of Frequency Response Analysis, FEA, and GA

2008 ◽  
Author(s):  
Arcady Soloviev ◽  
Anton Bychkov ◽  
Maria Shevtsova
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Elastic Constants ◽  
Orthotropic Materials ◽  
Vibration Modes ◽  
Dynamic Tests ◽  
Good Efficiency ◽  
Static Tests ◽  
Orthotropic Composite

The number of engineering problems includes the identification of anisotropic composite elastic constants determination. We developed an experimentally - analytical technique for identification of all elastic constants of orthotropic materials. The offered technique is substantially based on measurement of eigenfrequencies and semi quantitative analysis of natural vibration modes, instead of wave propagation speed and fields of vibrational displacement used by other acoustic methods. The developed method of the elastic composite and piezoelectric materials properties identification is implemented in linked MATLAB – Comsol Multiphysics combining the finite element analysis (FEA) of oscillations dynamics and minimization of some functional, which type is determined by particularity of a solved problem. These techniques complement the early designed by authors’ FEM-based methods for orthotropic composite static tests. The offered dynamic tests include an evaluation of specimen’s frequency response, determination of natural frequencies and vibration modes of specimens both in natural experiments and numerical finite element simulations. The identification process consists of several stages. In series of static tests are determined all allowable modules. Further a complete matrix of elastic constant is constructed, but some modules specified by approximated values (in particular, interlaminar shear modules). A series of dynamic tests executed in which the periodical excitation of samples and the frequency response is recorded by means of piezoelectric actuators and sensors. Then on basis of early defined (in static tests and with use of mix rule) modules of composite and experimentally founded eigenfrequencies by means of FEM the vibration natural modes are identified. By combination of FEM, genetic algorithm (GA) and Levenberg-Marquardt minimization method the specification of composite mechanical properties is evaluated. Application of developed technique to orthotropic composite used in aviation structures (polymeric composite spar of the helicopter main rotor blade) is explicitly illustrated. The obtained results have shown a good efficiency of proposed identification methods. We demonstrate that proposed approach provides best reliability and shows small dependence on metering equipment precision.

Complete Determination of the Local Stress Field in Epitaxial Thin Films Using Single Microstructure

2011 ◽  
Vol 679-680 ◽  
pp. 213-216 ◽  
Author(s):  
Massimo Camarda ◽  
Ruggero Anzalone ◽  
Andrea Severino ◽  
Nicolò Piluso ◽  
Antonino La Magna ◽  
...  
Keyword(s):  
Thin Films ◽  
Finite Element ◽  
Stress Field ◽  
Residual Stresses ◽  
Local Stress ◽  
Epitaxial Thin Films ◽  
Complete Determination ◽  
Analytical Approaches ◽  
Local Stress Field

In this article, using finite element simulations and analytical approaches, we demonstrate that planar rotators[1] can be effectively used to determine both the uniform and gradient residual stresses in thin films with higher accuracy compared to other microstructures.

Advances in the Chromatographic Separation and Determination of Bioactive Compounds for Assessing the Nutrient Profile of Nuts

2020 ◽  
Vol 16 ◽  
Author(s):  
Natasa P. Kalogiouri ◽  
Natalia Manousi ◽  
Erwin Rosenberg ◽  
George A. Zachariadis ◽  
Victoria F. Samanidou
Keyword(s):  
Fatty Acids ◽  
Phenolic Compounds ◽  
Bioactive Compounds ◽  
High Performance ◽  
Unsaturated Fatty Acids ◽  
Nutritional Deficiencies ◽  
Analytical Technique ◽  
High Volatility ◽  
Analytical Approaches

Background:: Nuts have been incorporated into guidelines for healthy eating since they contain considerable amounts of antioxidants and their effects are related to health benefits since they contribute to the prevention of nutritional deficiencies. The micronutrient characterization is based mainly on the determination of phenolics which is the most abundant class of bioactive compounds in nuts. Terpenes constitute another class of bioactive compounds that are present in nuts and show high volatility. The analysis of phenolic compounds and terpenes are very demanding tasks that require optimization of the chromatographic conditions to improve the separation of the components. Moreover, nuts are rich in unsaturated fatty acids and they are therefore considered as cardioprotective. Gas chromatography is the predominant instrumental analytical technique for the determination of derivatized fatty acids and terpenes in food matrices, while high performance liquid chromatography is currently the most popular technique for the determination of phenolic compounds Objective:: This review summarizes all the recent advances in the optimization of the chromatographic conditions for the determination of phenolic compounds, fatty acids and terpenes in nuts Conclusion:: The state-of-the art in the technology available is critically discussed, exploring new analytical approaches to reduce the time of analysis and improve the performance of the chromatographic systems in terms of precision, reproducibility, limits of detection and quantification and overall quality of the results

Tribology of rail bogie

2018 ◽  
Vol 77 (4) ◽  
pp. 230-240
Author(s):  
D. P. Markov
Keyword(s):  
Contact Fatigue ◽  
Basic Element ◽  
Difficult Problem ◽  
Railway Track ◽  
Rolling Stock ◽  
Kinematic Parameters ◽  
Approximate Estimation ◽  
Railway Bogie ◽  
Classical Calculation

Railway bogie is the basic element that determines the force, kinematic, power and other parameters of the rolling stock, and its movement in the railway track has not been studied enough. Classical calculation of the kinematic and dynamic parameters of the bogie's motion with the determination of the position of its center of rotation, the instantaneous axes of rotation of wheelsets, the magnitudes and directions of all forces present a difficult problem even in quasi-static theory. The paper shows a simplified method that allows one to explain, within the limits of one article, the main kinematic and force parameters of the bogie movement (installation angles, clearance between the wheel flanges and side surfaces of the rails), wear and contact damage to the wheels and rails. Tribology of the railway bogie is an important part of transport tribology, the foundation of the theory of wheel-rail tribosystem, without which it is impossible to understand the mechanisms of catastrophic wear, derailments, contact fatigue, cohesion of wheels and rails. In the article basic questions are considered, without which it is impossible to analyze the movement of the bogie: physical foundations of wheel movement along the rail, types of relative motion of contacting bodies, tribological characteristics linking the force and kinematic parameters of the bogie. Kinematics and dynamics of a two-wheeled bogie-rail bicycle are analyzed instead of a single wheel and a wheelset, which makes it clearer and easier to explain how and what forces act on the bogie and how they affect on its position in the rail track. To calculate the motion parameters of a four-wheeled bogie, it is represented as two two-wheeled, moving each on its own rail. Connections between them are replaced by moments with respect to the point of contact between the flange of the guide wheel and the rail. This approach made it possible to give an approximate estimation of the main kinematic and force parameters of the motion of an ideal bogie (without axes skewing) in curves, to understand how the corners of the bogie installation and the gaps between the flanges of the wheels and rails vary when moving with different speeds, how wear and contact injuries arise and to give recommendations for their assessment and elimination.

Determination of Charge Coefficient of Piezoelectric Films Using a Combined Finite Element Model and Dynamic Loading Technique

2020 ◽  
Vol 835 ◽  
pp. 229-242
Author(s):  
Oboso P. Bernard ◽  
Nagih M. Shaalan ◽  
Mohab Hossam ◽  
Mohsen A. Hassan
Keyword(s):  
Finite Element ◽  
Dynamic Loading ◽  
Material Properties ◽  
Accurate Determination ◽  
Substrate Material ◽  
Experimental Results ◽  
Piezoelectric Composite ◽  
Piezoelectric Film ◽  
Piezoelectric Charge

Accurate determination of piezoelectric properties such as piezoelectric charge coefficients (d33) is an essential step in the design process of sensors and actuators using piezoelectric effect. In this study, a cost-effective and accurate method based on dynamic loading technique was proposed to determine the piezoelectric charge coefficient d33. Finite element analysis (FEA) model was developed in order to estimate d33 and validate the obtained values with experimental results. The experiment was conducted on a piezoelectric disc with a known d33 value. The effect of measuring boundary conditions, substrate material properties and specimen geometry on measured d33 value were conducted. The experimental results reveal that the determined d33 coefficient by this technique is accurate as it falls within the manufactures tolerance specifications of PZT-5A piezoelectric film d33. Further, obtained simulation results on fibre reinforced and particle reinforced piezoelectric composite were found to be similar to those that have been obtained using more advanced techniques. FE-results showed that the measured d33 coefficients depend on measuring boundary condition, piezoelectric film thickness, and substrate material properties. This method was proved to be suitable for determination of d33 coefficient effectively for piezoelectric samples of any arbitrary geometry without compromising on the accuracy of measured d33.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

scholarly journals Characterization and Quantification of Selenoprotein P: Challenges to Mass Spectrometry

2021 ◽  
Vol 22 (12) ◽  
pp. 6283
Author(s):  
Jérémy Lamarche ◽  
Luisa Ronga ◽  
Joanna Szpunar ◽  
Ryszard Lobinski
Keyword(s):  
Mass Spectrometry ◽  
State Of The Art ◽  
Animal Health ◽  
Primary Standard ◽  
Selenoprotein P ◽  
Primary Standards ◽  
Analytical Approaches ◽  
Careful Investigation ◽  
Accurate Quantification

Selenoprotein P (SELENOP) is an emerging marker of the nutritional status of selenium and of various diseases, however, its chemical characteristics still need to be investigated and methods for its accurate quantitation improved. SELENOP is unique among selenoproteins, as it contains multiple genetically encoded SeCys residues, whereas all the other characterized selenoproteins contain just one. SELENOP occurs in the form of multiple isoforms, truncated species and post-translationally modified variants which are relatively poorly characterized. The accurate quantification of SELENOP is contingent on the availability of specific primary standards and reference methods. Before recombinant SELENOP becomes available to be used as a primary standard, careful investigation of the characteristics of the SELENOP measured by electrospray MS and strict control of the recoveries at the various steps of the analytical procedures are strongly recommended. This review critically discusses the state-of-the-art of analytical approaches to the characterization and quantification of SELENOP. While immunoassays remain the standard for the determination of human and animal health status, because of their speed and simplicity, mass spectrometry techniques offer many attractive and complementary features that are highlighted and critically evaluated.

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